Cryopreservation is a process by which samples such as biological materials are frozen under controlled conditions and stored at low temperatures. Cryopreservation is frequently used to store cell cultures, for example, which must be maintained over time in order to ensure a ready supply of cells for re-growth and experimentation. Cells for such purposes are routinely frozen in suspension in industrial cryovials. Freezing methods have been developed to minimize the impact of osmotic shock and intracellular ice crystal formation, two factors that contribute to cell death during the freezing process and frozen storage.
Under current methods, however, a significant number of cells are still lost to cell death during the freeze-thaw process. Cell loss can be substantial in homogeneous cell suspensions, and cell loss increases as the system undergoing preservation becomes more complex (e.g., tissues and organs). Moreover, current methods are insufficient for effective large-scale cryopreservation of cell samples and tissues in a multi-vessel format, for example as adherent cells in a multiwell format. Unacceptably high well-to-well variability as well as unsatisfactory overall post-thaw viability currently render large-scale processes for bulk freezing of cells in multi-well plates commercially non-viable.